Review What You Already Have
I know. It seems basic. But I can't stress enough how many brick walls are breached with information that the researcher already had tucked away in files, boxes or computer disks. Information that you found a few years ago may include names, dates or other details that now provide clues given new facts that you've since uncovered. Organizing your files and reviewing your facts may uncover just the clue you're looking for.
Go Back to the Original Source
Many of us are guilty when transcribing information or recording notes of only including the facts we deem important at the time. You may have kept the names and dates from that old census record, but did you also keep track of other information such as years of marriage and country of parent's origin? Or, perhaps, you misread a name or misinterpreted a relationship? If you haven't already, be sure to go back to the original records, making complete copies and transcriptions and recording all clues - however unimportant they may seem right now.
Broaden Your Search
When you're stuck on a particular ancestor, a good strategy is to extend your search to family members and neighbors. When you can't find a birth record for your ancestor that lists his/her parents, maybe you can locate one for a sibling. Or, when you've lost a family between census years, try looking for their neighbors. You may be able to identify a migration pattern, or a mis-indexed census entry that way. Often referred to as "cluster genealogy," this research process can often get you past tough brick walls.
Question and Verify
Many brick walls are built from incorrect data. In other words, your sources may be leading you in the wrong direction through their inaccuracy. Published sources often contain transcription errors, while even original documents may contain misinformation, whether purposefully or accidentally given. Try to find at least three records to verify any facts that you already know and judge the quality of your data based on the weight of the evidence.
Check Name Variations
Your brick wall may just be something as simple as looking for the wrong name. Variations of last names can make research complicated, but be sure to check all spelling options. Soundex is a first step, but you can't count on it entirely - some name variations can actually result in different soundex codes. Not only can the surnames be different, but the given name may be different as well. I've found records recorded under initials, middle names, nicknames, etc. Get creative with name spellings and variations and cover all the possibilities.
Learn Your Boundaries
Even though you know that your ancestor lived on the same farm, you may still be looking in the wrong jurisdiction for your ancestor. Town, county, state and even country boundaries have changed over time as populations grew or political authority changed hands. Records were also not always registered in the locality where your ancestors lived. In Pennsylvania, for example, births and deaths can be registered in any county, and many of my Cambria county ancestor's records were actually located in neighboring Clearfield county because they lived closer to that county seat and found it a more convenient trip. So, bone up on your historical geography and you just may find a new route around your brick wall.
Ask for Help
Fresh eyes can often see beyond brick walls, so try bouncing your theories off other researchers. Post a query to a Web site or mailing list which focuses on the locality in which the family lived, check with members of the local historical or genealogical society, or just talk through it with someone else who loves family history research. Be sure to include what you already know, as well as what you'd like to know and which tactics you've already tried.